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OneToOne mapping on same table [message #631443]

Thu, 07 October 2010 14:47

Matti Hansson

Messages: 68
Registered: July 2009

Member

Hi!
I have an object model with a Unit having a one-to-one relation to a UnitIdentifier. In the database, all fields of both classes are contained within a single table.

It's easy enough to simply map those classes like usual and call it a day, but this will result in two queries to the database: select the fields of Unit in the correct row, and then select the fields of UnitIdentifier in the same row.

This is fine, I guess, but it makes me hurt a bit inside Razz

Is there a way to do this using a single fetch?

Thanks!
/Matti

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Re: OneToOne mapping on same table [message #631699 is a reply to message #631443]

Fri, 08 October 2010 13:59

Chris Delahunt

Messages: 1389
Registered: July 2009

Senior Member

EclipseLink has a @JoinFetch annotation you can used on a relationship, or you can use fetch join in JPQL for particular relationships. What is the table and entity setup for these two classes? Do they share a row, are they using inheritance, etc?

Best Regards,
Chris

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Re: OneToOne mapping on same table [message #632019 is a reply to message #631443]

Mon, 11 October 2010 08:49

Matti Hansson

Messages: 68
Registered: July 2009

Member

Thanks for the reply, Chris, but @JoinFetch was not quite what I was after. However, I found that @Embeddable/@Embedded does exactly what I want.
Problem solved.
/Matti

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